Small userland helper functions for PHP filter extension. filter_validate_var() is a shortcut for filter_var() with built-in validation filters. It accepts validation filter names such as "email", "int", "float", "url", and "ip", and hides FILTER_VALIDATE_* constants from application code. filter_callback_var() is a shortcut for FILTER_CALLBACK.…

01-usage.php

<?php

declare(strict_types=1);

require __DIR__ . '/filter_helpers.php';

$age = filter_validate_var('20', 'int', [
    'options' => [
        'min_range' => 18,
        'max_range' => 120,
    ],
]);

var_dump($age); // int(20)

$email = filter_validate_var('taro@example.com', 'email');

var_dump($email); // string(16) "taro@example.com"

function validate_message(string $value): string|false
{
    if ($value === '') {
        return false;
    }

    if (mb_strlen($value) > 1000) {
        return false;
    }

    return $value;
}

$message = filter_callback_var('お問い合わせ内容です。', 'validate_message');

var_dump($message);

02-filter_validate_var.php

<?php

declare(strict_types=1);

/**
 * Returns the FILTER_VALIDATE_* constant for a validation filter name.
 *
 * This helper intentionally accepts only validation filter names.
 * It does not accept sanitize filters or FILTER_CALLBACK.
 */
if (!function_exists('filter_validation_id')) {
    function filter_validation_id(string $filter): int
    {
        return match ($filter) {
            'email' => FILTER_VALIDATE_EMAIL,
            'int' => FILTER_VALIDATE_INT,
            'float' => FILTER_VALIDATE_FLOAT,
            'bool', 'boolean' => FILTER_VALIDATE_BOOL,
            'url' => FILTER_VALIDATE_URL,
            'domain' => FILTER_VALIDATE_DOMAIN,
            'ip' => FILTER_VALIDATE_IP,
            'mac' => FILTER_VALIDATE_MAC,
            'regexp', 'regex' => FILTER_VALIDATE_REGEXP,

            default => throw new InvalidArgumentException(
                "Unknown validation filter: {$filter}"
            ),
        };
    }
}

/**
 * Validates a value using a named built-in validation filter.
 *
 * This is a small shortcut for:
 *
 *     filter_var($value, FILTER_VALIDATE_*, $options)
 *
 * The second argument is a validation filter name such as:
 *
 *     'email', 'int', 'float', 'bool', 'url', 'ip'
 *
 * It intentionally does not accept FILTER_VALIDATE_* constants.
 */
if (!function_exists('filter_validate_var')) {
    function filter_validate_var(
        mixed $value,
        string $filter,
        array|int $options = 0,
    ): mixed {
        return filter_var(
            $value,
            filter_validation_id($filter),
            $options
        );
    }
}

/**
 * Applies a custom callback filter to a value.
 *
 * This is a small shortcut for:
 *
 *     filter_var($value, FILTER_CALLBACK, ['options' => $callback])
 *
 * This function is not validation-specific. The callback contract is the same
 * as FILTER_CALLBACK: the callback return value becomes the filter result.
 */
if (!function_exists('filter_callback_var')) {
    function filter_callback_var(
        mixed $value,
        callable $callback,
    ): mixed {
        return filter_var($value, FILTER_CALLBACK, [
            'options' => $callback,
        ]);
    }
}

03-usage2.php

<?php

$input = [
    'email' => 'taro@example.com', // valid
    'age' => '17',                 // invalid: less than 18
    'message' => '',               // invalid: empty string
];

$app_spec = [
    'email' => 'email',

    'age' => [
        'rule' => 'int',
        'options' => [
            'min_range' => 18,
            'max_range' => 120,
        ],
    ],

    'message' => 'message',
];

$custom_rule_registry = [
    'message' => 'validate_message',
];

$result = validate_input(
    input: $input,
    app_spec: $app_spec,
    custom_rule_registry: $custom_rule_registry,
);

var_dump($result);

/**
 * アプリ仕様をもとに入力値を検証する。
 *
 * 標準の validation filter は filter_validate_var() に渡す。
 * 独自ルールは $custom_rule_registry から callback を解決して filter_callback_var() に渡す。
 */
function validate_input(
    array $input,
    array $app_spec,
    array $custom_rule_registry = [],
): array {
    $result = [];

    foreach ($app_spec as $field => $field_spec) {
        $rule = rule_from_field_spec($field_spec);
        $options = options_from_field_spec($field_spec);

        $value = $input[$field] ?? null;

        if (isset($custom_rule_registry[$rule])) {
            $result[$field] = filter_callback_var(
                value: $value,
                callback: $custom_rule_registry[$rule],
            );

            continue;
        }

        $result[$field] = filter_validate_var(
            value: $value,
            filter: $rule,
            options: $options,
        );
    }

    return $result;
}

/**
 * フィールド仕様からルール名を取り出す。
 */
function rule_from_field_spec(string|array $field_spec): string
{
    if (is_string($field_spec)) {
        return $field_spec;
    }

    if (!isset($field_spec['rule']) || !is_string($field_spec['rule'])) {
        throw new InvalidArgumentException('Field spec must have a string rule.');
    }

    return $field_spec['rule'];
}

/**
 * フィールド仕様から filter_var() 用の options を取り出す。
 */
function options_from_field_spec(string|array $field_spec): array|int
{
    if (is_string($field_spec)) {
        return 0;
    }

    return $field_spec['options'] ?? 0;
}

/**
 * 独自バリデーションルール。
 *
 * FILTER_CALLBACK と同じく、戻り値がそのまま検証結果になる。
 */
function validate_message(mixed $value): string|false
{
    if (!is_string($value)) {
        return false;
    }

    if ($value === '') {
        return false;
    }

    return $value;
}